From 8f1c6bdc97c864970f9ec0054b011896de1a92c5 Mon Sep 17 00:00:00 2001
From: Quentin Gliech <quenting@element.io>
Date: Mon, 18 Aug 2025 09:56:37 +0200
Subject: [PATCH 1/2] Allow enabling MSC4108 when the stable MAS integration is
 enabled

---
 synapse/config/experimental.py | 8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/synapse/config/experimental.py b/synapse/config/experimental.py
index c4181a6b0b3..c1631f39e3d 100644
--- a/synapse/config/experimental.py
+++ b/synapse/config/experimental.py
@@ -535,11 +535,15 @@ def read_config(
             "msc4108_delegation_endpoint", None
         )
 
+        auth_delegated = self.msc3861.enabled or (
+            config.get("matrix_authentication_service") or {}
+        ).get("enabled", False)
+
         if (
             self.msc4108_enabled or self.msc4108_delegation_endpoint is not None
-        ) and not self.msc3861.enabled:
+        ) and not auth_delegated:
             raise ConfigError(
-                "MSC4108 requires MSC3861 to be enabled",
+                "MSC4108 requires MSC3861 or matrix_authentication_service to be enabled",
                 ("experimental", "msc4108_delegation_endpoint"),
             )
 

From b7468426b66c68a04246db25e8b2cd2cd0876081 Mon Sep 17 00:00:00 2001
From: Quentin Gliech <quenting@element.io>
Date: Mon, 18 Aug 2025 09:58:58 +0200
Subject: [PATCH 2/2] Newsfile

---
 changelog.d/18832.bugfix | 1 +
 1 file changed, 1 insertion(+)
 create mode 100644 changelog.d/18832.bugfix

diff --git a/changelog.d/18832.bugfix b/changelog.d/18832.bugfix
new file mode 100644
index 00000000000..bd87cacde70
--- /dev/null
+++ b/changelog.d/18832.bugfix
@@ -0,0 +1 @@
+Allow enabling MSC4108 when the stable Matrix Authentication Service integration is enabled.